Build a shower pan by applying a sloped layer of mortar to the floor, adding a layer of chlorinated polyethylene membrane, placing metal lath and covering with a second layer of sloped mortar. Finish the shower pan with a layer of ceramic tile. Building a shower pan costs about the same as installing a fiberglass pan but involves much more work. Be cautious in building the pan, as poor design and workmanship lead to leaks.
Prior to beginning construction, check the support under the floor. A concrete shower pan weighs up to 1,000 pounds and may require reinforcement supports. Any particle board underlayment requires removal before installing the concrete pan.
Slope the first layer of mortar 1/4 inch for every foot of horizontal length toward the drain. Maintain the same slope for subsequent layers to ensure water does not pool on the surface. Smooth the concrete with a steel trowel and follow the manufacturer’s directions for drying time before proceeding to the next step.
The chlorinated polyethylene layer prevents leaks. It extends from the drain up the sides of the wall and over any curbs. The material is available in 6-foot widths. Showers with larger floors require joining pieces of the film using special techniques to prevent leaks.